Chemical in Plastics May Alter Boys' Genitals Before Birth

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Baby boys who are exposed in the womb to a chemical used in soft
plastics may show small signs of altered genital development,
according to new research published today.

The study, which included more than 700 infants in four U.S.
cities, is the largest of its kind to date. It confirms earlier
findings in humans and animals that exposure to certain types of
chemicals called phthalates may lead to changes in the way
the male reproductive tract develops, said Dr. Russ Hauser, an
epidemiologist at the Harvard School of Public Health, who was
not involved in the new study.

Phthalates are a large group of industrial chemicals used in a
variety of consumer products, such as food packaging, flooring,
perfumes and lotions.

The changes seen in the babies in the study were small, said lead
author Shanna Swan, a reproductive health scientist at Mount
Sinai Hospital in New York.

In the study, the researchers measured pregnant women's levels of
11 compounds that are formed in the body when phthalates are
broken down. The researchers looked at the levels of these
compounds in the women's urine during the first trimester of
pregnancy, which is the period when the fetal reproductive tract
begins to develop.

They found that newborn boys who were exposed in the womb to the
highest levels of one phthalate, called diethylhexyl phthalate
(DEHP), had an "anogenital distance" that was 4 percent shorter
than that of the boys born to women with the lowest levels.
Anogenital distance — a measure of the length between the anus
and the genitals — is a marker of reproductive health, wrote the
study authors.

The distance between the anus and the genitals is typically 50 to
100 percent longer in males than in females, and a shortened
anogenital distance may signal incomplete masculinization, the
researchers said.

It's unclear whether the slight alterations seen in the babies in
the study could be permanent, or could result in any reproductive
health issues. Animal studies suggest that a shortened anogenital
distance at birth may signal reproductive abnormalities later in
life, and previous studies in humans have linked shorter
anogenital distance with testicular abnormalities and semen
problems in men. But the researchers would have to follow up with
the boys in the study in adulthood to see whether their reproductive
health is affected, Swan said.

The researchers found no association between genital development
and levels of several other phthalates in boys. None of
phthalates tested were associated with altered genitalia in baby
girls.

In rodents, previous research has shown that some phthalates,
including DEHP, block the production of male sex
hormones by the testes.

The United States banned the use of DEHP and two
other phthalates in children's toys and products in 2008 due
to reproductive health concerns. But the chemical may still be
used in food-processing and packaging materials, and in medical
tubing and supplies, according to the study.

A spokesperson from the American Chemistry Council, which
represents chemical manufacturers, said that people could be
exposed to phthalates from food processing that involves storage
in flexible plastic or rubber bags or containers, but most
plastic food packaging and storage items are now made with
plastics that don’t contain DEHP.

"Information collected by the Centers for Disease Control and
Prevention over the last 10 years indicates that, despite the
fact that phthalates are used in many products, exposure from all
sources combined is extremely low — much lower than the levels
established as safe by scientists at regulatory agencies," a
spokesperson for the council wrote in an email to Live Science.

Although DEHP is still found in the bodies of most Americans,
people's levels of the chemical have decreased over the past
decade, as DEHP has been replaced with other plasticizers, Swan
said. The levels of DEHP seen in the pregnant women in this
newest study, which were measured from urine samples collected
between 2010 and 2012, were about 50 percent lower than the
levels in urine from mothers obtained in a previous study,
between 2000 and 2002, Swan said.

Smaller studies that Swan conducted in 2005 and 2008 also found
that prenatal exposure to DEHP at higher levels was associated
with altered male genital development.

"We are finding a significant association between male anogenital
distance and phthalates at lower and lower levels, which suggests
that there may be no safe level of exposure," she said.

While it's extremely difficult to avoid all exposure to
plasticizer chemicals, Swan suggested that opting for unprocessed
foods could help people reduce their exposure to DEHP and other
phthalates used in the packaging and processing of
food [L1] .

The findings were published online today (Feb. 19) in the journal
Human Reproduction.